BDD

Ordered binary decision diagrams (OBDDs, often simply called BDDs)
are a technique, originally published by Randy Bryant, for the
efficient simplification of Boolean expressions. In ACL2 we combine
this technique with rewriting to handle arbitrary ACL2 terms that
can represent not only Boolean values, but non-Boolean values as
well. In particular, we provide a setting for deciding equality of
bit vectors (lists of Boolean values).

An introduction to BDDs for the automated reasoning community may
be found in ``Introduction to the OBDD Algorithm for the ATP
Community'' by J Moore, Journal of Automated Reasoning (1994),
pp. 33-45. (This paper also appears as Technical Report #84 from
Computational Logic, Inc.)

Further information about BDDs in ACL2 can be found in the
subtopics of this documentation section. In particular,
see bdd-introduction for a good starting place that provides a
number of examples.

See hints for a description of :bdd hints. For quick
reference, here is an example; but only the :vars part of the
hint is required, as explained in the documentation for hints.
The values shown are the defaults.